The invention relates to a balloon catheter with an indispensable covering sleeve being movable along the catheter shaft. The invention also relates to a delivery device for a balloon-expandable stent.
In the balloon catheter technology, it is known to use balloon catheters with fixed balloon lengths. Many medical procedures require the application of several balloon catheters with different balloon lengths. If an intervention demands, for instance, two differently long balloons, it is necessary to change the balloon catheter or to use the same balloon sequentially. The change of a balloon catheter is, however, very costly while sequential action is time consuming. Moreover, the risk of injury for the patient is increased or insufficient dilatations might be achieved.
A balloon catheter is also an instrument of common use for the transport and expansion of a balloon-expandable prosthesis such as a stent, which is implanted for maintaining the patency of a vessel. Here, the length of the balloon has to be chosen in dependence on the length of the stent in order to avoid inappropriate expansion of the stent or damage to the vessel. This inevitably leads to the costly need of a plurality of balloon catheters with different balloon lengths to correctly and safely apply stents.
The document EP 0 727 194 A1 shows a balloon catheter in which an indispensable covering sleeve can take two different positions. In its proximal end position, the covering sleeve uncovers the full balloon length for expansion, while in its distal end position, it covers a proximal portion of the balloon and prevents this from an expansion to the nominal balloon diameter. With such a balloon catheter, a selection can be made between two different balloon lengths. The distal end position is secured by friction fit upon pushing the covering sleeve onto an enlarged portion of the catheter shaft. The covering sleeve also comprises a tampered distal end without armature means which in use, however, is expanded by the pressurized dilatation balloon. The fully expanded part of the dilatation balloon then applied a proximal directed force against the covering sleeve which might cause it to migrate. Intermediate positions of the covering sleeve and consequently intermediate values of the balloon length cannot be selected with this catheter. In such a case, the position of the covering sleeve would not be secured and could migrate under the dilation pressure.
All documents cited herein, including the foregoing, are incorporated herein by reference in their entireties for all purposes.